What is Dc: Definition and 1000 Discussions

I'm working on a senior design project. Currently I'm having some issues with sizing a motor for a large robot; everywhere I look I get different advice. I have a motor that I think will work but would appreciate some input. The specs are for our robot are as follows: mass = 350 lb = 158.8 kg...

I'm currently trying to test the motors I bought for a robotics project to see if they'll work for our application and they seem to be much weaker than what should be expected based on the specs. During test, the battery is hooked directly to the motor and I'm measuring the current draw and the...

I've been stuck on what I would of thought was a simple/common question but I can't seem to find an answer anywhere. I'm confused as to how a DC current propagates along a conductor (wire) in terms of it's E/H field. I understand that it is these fields that cause the propagation of current...

How do i get 250v dc power supply?? Should I use lots of batteries or is there an easier way?

Homework Statement In the Figure Q1 (c), the switch S was closed for very long time before it is opened at time t = 0. Find the value of vC(t) and iL(t) at t = 0+ c L i.e. immediately after the switch was opened. Homework Equations V = IR The Attempt at a Solution From DC steady state, we...

hi there, I have 3 dc motors (12v-5 ampere)that are connected each with a speed reducer gearbox, actually I want to control these motors with a JOY-STICK switch just controlling there movements in fixed speed, should I use a pwm circuit to drive them or a simple 3-axes joy-stick is enough? if...

1)i need to step down the DC voltage 48v 75amp to 24 v 75amp. for above any ready made convertor is available in market? 2)i have a dc source 30Vdc 10amp, i need to charge a battery using that, i looking for charging circuit please help. rajesh.p

< Moderator Note -- thread moved from ME forum to Homework Help/Engineering > Hi, I Am an electrical engineering student and I want to make a 12 DC car jack for my senior project, but till now I couldn't find the informations I need to start the project. How to calculate the force and torque...

Homework Statement Hello, I am a 6th grade student trying to build a DC motor for the science fair. My hypothesis is that the dc motor will run faster if I place batteries in parallel versus batteries in a series. Is there an equation i can look at to explain what is happening? the mootr...

Guys Can you give me what is the difference between construction in 120 degrees pole arc and 180 degrees pole arc brushless DC motor with trapezoidal bldcm?

I have recently taken apart a few old DVD drives to see if there were any stepper motors available for a Raspberry Pi project I am currently working on. When I opened one of the older drives I found a motor which was unlike the others as it only seemed to have two wires going directly to the...

I have seen a link in this forum http://ww1.microchip.com/downloads/en/DeviceDoc/22263A.pdf that denotes an IC to control a brushless DC motor. How to connect it with a 555 timer? Can anyone help me with the entire circuit diagram? Thanks in advance.

Hi everybody! I am trying to implement current control of a DC motor using a PI controller and was having a few questions. I am supplying 19V as input voltage (and capable of supplying current upto 2A) to the H- bridge and the controlling is done via a microcontroller using PWM. When I connect...

http://i.imgur.com/nhBN1RJ.jpg << Huge image replaced with URL by Moderator >> The attempt at a solution I have been able to find V(0+)=12 V(0-)=12 I(0-)=4 Not able to find a suitable way to get a general solution for Vc and Ix

I have attached a 12v DC electric drill moter to a fishing pole. I need a 12v dc motor controler or PWM that will allow me to cut the rpm's down from 550 rpm to about 20 to 100 rpm. less then 20 would work better for bottom fishing. I believe a PWM would work but I am not sure as to a...

Hello, I am reading a book on Power Electronic and got confused on the actual interpretation of ac and dc power. From basic circuit analysis, I already know that the average power delivered to a resistive load by a sinusoidal signal is : P_{ac} = \frac{V^{2}_{rms}}{R}. When talking about a pure...

Hi All, Much respect and admiration to the majority of you highly ordered beings. My question is a simple one I hope, how can I get a 24v DC motor to reverse ~half a rotation when forward RPM get low (0-10)? Thanks

Residential DC power distribution, well that’s the end goal. The main question is about stepping down a 24v 4amp lead acid deep cycle battery bank to accommodate normal DC usage voltage. For example 24v 4amp too: 12v 1a, 5v 400ma, 9v .4a, 12v 2a. Was thinking of making adjustable outlets so...

Hello All, I have a stater that puts out AC voltage, at max RPM it produces 40 volts. I have a voltage regulator installed parallel and it controls volts to max 14+v AC. I need to run an 80 watt 12V DC cooling fan so I installed a little block that has 4 diodes inside. Possibly this is...

Hi, I'm trying to use a small PM DC motor as a generator to convert mechanical energy to electrical energy. I couple that small generator to another DC motor with spur gears and I measure the current of that small generator while it is driven by the DC motor at fixed speed. The circuit of...

Hi guys: I like physics but i have many questions concerning electricity and magnetism. 1- Do we accelerate electrons when increasing the voltage in a DC circuit. 2-What does it mean when we say there is a potential difference across the plates of the capacitor. 3- What is the potential and...

while drawing the dc load line , , we take VCE = 0 and mark it as saturation point but but in saturation state VCE is very small but not zero..! I actually want to make clear that whether its a fact or is it just an assumption to find out saturation point..?? similarly for the cutoff point we...

I noticed that common technology such as brushless DC motors use AC to drive them. What exactly makes DC brushless motors different from AC motors if they both ultimately take in AC? Why even refer to DC brushless motors as DC motors if they're not even driven by DC? I understand the source is a...

Hi, I am planning to run a DC motor using a super capacitor. The specification of the motor are: Voltage : 90V - 120 V DC Current : 15 A Duration : Should run for atleast 10 seconds. I have finalized this super capacitor from maxwell for the above operation...

Thermoelectric generator induce DC current and I just wants to understand how can a transformer step up DC. If there is something else please make me clear.

How can velocity uniformity in dynamos and motors be explained? What's the mechanism of that happening ? I'm aware that Newton's first law is involved in that situation where an equal and opposite torque must act on the coil during its rotation so the net torque is Zero and the coil keeps...

Hi, I have been looking into Tesla's work and his self claimed "non-Hertzian" waves, some called electrostatic or dieletric pressures waves or rays eletric induction (magnetic and dielectric). I am also interestted in negative resistance systems, transiet phenomenon (pulse wave) and...

Homework Statement DC analysis is required for the question in attachment. Vz=6V B=100 Vbe=0.7V Homework Equations The Attempt at a Solution I tried to find the result using the currents that were defined by the transistor. I found a result that was nonsense, the base current...

Hello everyone! In the following speed-torque characteristic of a DC shunt motor, we see that if the speed exceeds a certain value, then the machine becomes a generator. I don't understand something. How is it possible for the machine to have a negative torque and a positive speed...

Hello. I'm trying to design a AC to DC LED driver with PWM dimming. I have a design that I can use with the LM3406HV but I would like to design something that I can wire up 110V AC mains line. With the LM3406HV I need a DC power supply. I was thinking about using a switching power supply but if...

I'm using a DC power supply connected to a TPIC 1021 chip(basically a serial transceiver). I need 12V to power the chip and my DC power supply is equipped with 2 knobs,one changes the voltage and the other changes the current. For some reason,when I get to 5V and turn the volt knob...

Hi everyone, I have not designed a circuit for, well, decades now, so I’m hoping you can provide me with a bit of guidance. I have a solar power system with a 48V battery array. (System also includes an inverter [AC->DC + DC->AC], backup generator, solar panels, charge controller, etc..)...

Say I was run a homemade motor using a 9v battery, and then ran it again using two 9v batteries... would it go faster with the 18v?? Cheers

I am building a two coil DC motor as a project. I have two neodymium magnets, an aluminium split ring, and alligator clips acting as brushes, connected to a 9v battery. For some reason it is not working and I cannot figure out why. Can anyone think of something I may be doing wrong. I can post...

Hi I am trying to calculate the efficiency of my DC motor. I know that efficiency is: Power Out / Power In * 100 I have been told by my teacher that Power In is calculated by the following formula, Power In = Power * Time And Power Out is; Power Out = Mass * Gravity * Height...

An inductor of negligible resistance and an inductance of 0.2 H is connected in series with a 330 Ω resistor to a 12V d.c. supply. Determine: (a) the time constant of the circuit (b) the voltage drop across the inductor after two time constants (c) the voltage drop across the resistor after...

Homework Statement http://postimg.org/image/8oweasluj/ Each rectangle in the figures represents a resistor with resistance=2.9kΩ. a) What is the net resistance of the circuit of Fig 1 connected to the battery? Each resistance has R=2.9 kΩ. b) What is the current flowing into the...

how would you calculate the resistance required for a resistor which is in series with a generator (DC motor in reverse) to achieve a certain torque from the generator? Eg, there's a torque of 30kN acting on a 100kW generator while it moves at 50RPM. The is the same mechanism as electric...

Ok i started working with capasitors and inductors and i have a question. The capasitor is an open circuit to dc,right? Now the questions: a)If the current of capasitor is 0 how can it store energy?I know that we use this:1/2 C V^2 but it seems weird that with just stable voltage we store...

I want to design a bidirectional DC motor , so use four transistors in the H bridge circuit. I can understand the first circuit, but for the second, I can't understand why input signal , eg: A, is connected to the same side of transistors? What is the differences, which one I should...

a. the commutator b. the brushes c. the field d. the armature I know this is a basic question, its off an old exam paper I am looking at. I think its the brushes because if it doesn't have brushes, then its a brushless dc motor, which isn't basic right? Thanks for your help! :shy:

I have a 1.5 hp dc motor that I am going to use water power to turn . How much power can I expect from this . It is just a summer fun project .

Hello, I'm new here and I'm not sure if this post belongs here or in a physics forum, but here goes. I'm working on a project to power a 6W (bulb input power) UVC bulb from a low voltage DC battery source (4.5 VDC). This of course requires a high efficiency ballast between the DC supply...

What would be the easiest way to raise the voltage of a DC source? (Mainly batteries) For example, say I have a 9V battery and would like to convert it to 120VDC. What would be the best way of doing this without just hooking 13 or 14 9V batteries is series? If this is impractical, please feel...

Homework Statement http://puu.sh/7gYwk.png Consider the circuit shown above. Find the current Ia flowing through the resistor and the power for each element in the circuit. Which elements are absorbing power? Homework Equations P = V x I = I^2 x R = V^2 / R The Attempt at a...

12 volts DC will travel thru a Diode connected to 120 volt AC , but will it put any load on the battery? John

Hi everyone, first post. Just wanted to say I've been using parts of this forum for a long time for help in understanding all kinds of concepts, and have found it immensely helpful over the years. Thank you for all of your contributions! So, here goes with my hopefully very simple question...

i am middle of engg project . to make an automatic irrigation system ,using plc , main problem is humidity sensor which i am using gives out put of 0-5 volt but plc require more output for better results,...can anyone suggest a voltage amplifier or any circuit using op amp

Hi, I am looking for a compact (possibly a on-chip solution) high efficiency DC-DC dual converter powered by a USB 2 port. The aim is to supply a dual voltage to a logic circuit for driving audio signals from/through different channels, as in an audio switch I.e. MAX4910 or 4912. Any idea...

Hey, I hope I don't bother any of the serious electrical engineers, but I was wondering if anybody could help me with a project I'm working on. I want to build a generator that I can attach to my stationary bike that will charge my phone. It has a very simple design, two permanent magnets that...